A silicon carbide high-voltage power supply and its control method

Abstract

The present application discloses a silicon carbide high-voltage power supply and its control method, which relates to the technical field of high-voltage power supplies, and solves the problems that the integrated high-voltage power supply is not convenient for maintenance and repair, and the operation stability and lifespan of the integrated high-voltage power supply are easily affected by the outdoor operation environment due to the need to be all installed outdoors close to the load device. The method includes a silicon carbide MOSFET inverter control module and a boost rectifier high-voltage module with modular design. The silicon carbide MOSFET inverter control module and the boost rectifier high-voltage module are connected by a detachable cable. The silicon carbide MOSFET inverter control module and the boost rectifier high-voltage module can be installed at different positions over a long distance. The silicon carbide MOSFET inverter control module in the low-voltage part is installed indoors and is not easily affected by the outdoor environment. At the same time, it is convenient for control operation, inspection, maintenance, etc. The boost rectifier high-voltage module in the high-voltage part is installed outdoors far away close to the load device, which is convenient for high-voltage connection with the load device and avoids high-voltage safety hazards.

Description

Technical Field

[0001] This application relates to the technical field of high-voltage power supplies, and in particular to a silicon carbide high-voltage power supply and its control method. Background Art

[0002] A high-voltage power supply, belonging to special power supply equipment, is widely used in the field of environmental protection, such as pollution control in industries such as steel, cement, coal-fired power generation, and sewage treatment.

[0003] A high-voltage power supply usually includes a control circuit, a DC circuit, an inverter circuit, a boost circuit, a high-voltage rectifier circuit, etc., which contain many semiconductor devices. In recent years, with the development of electric vehicles and the new energy industry, the third-generation silicon carbide semiconductor technology has begun mass production and batch application. Silicon carbide MOSFET has a highly stable crystal structure and a relatively high energy band width. Its operating frequency is much higher than that of silicon semiconductor IGBT modules. At the same time, it has excellent high-temperature operating characteristics, low switching losses, and is very suitable for application in high-voltage power supplies, reducing power losses, improving power efficiency, and reducing the operating costs of users. At the same time, by applying silicon carbide MOSFET to the inverter circuit and increasing the operating frequency of the inverter, the volume of the high-voltage power supply transformer can be effectively reduced.

[0004] Existing high-voltage power supplies have a very high degree of integration. The control circuit, DC circuit, inverter circuit, boost circuit, high-voltage rectifier circuit, etc. are integrated into a whole, with high integration and small volume, and the installation space required on site is small, which has great advantages. However, when the high-voltage power supply is installed and operated outdoors, the ambient temperature changes greatly throughout the year. In summer, the ambient temperature is between +35°C and +50°C, and in winter, the ambient temperature is between -25°C and -45°C. Moreover, the humidity and the cleanliness of the air in the environment in different operating environments also vary greatly, resulting in significant differences in the reliability and lifespan of the high-voltage power supply under different environmental operations. When operating outdoors, if a high-voltage power supply fails in bad weather such as high temperature, rain, snow, and strong wind, it is extremely difficult to repair the integrated high-voltage power supply.

[0005] In addition, there will also be flammable and explosive occasions, such as in a steel mill, where a large amount of flammable and explosive gases such as carbon monoxide are generated in the process of converter steelmaking. A large number of circuits in the integrated high-voltage power supply require heat dissipation design, which is not conducive to the design and application in explosion-proof occasions. The low-voltage control and high-voltage part of the integrated high-voltage power supply are integrated together, which also has certain potential safety hazards.

[0006] Based on the application in special occasions, factors such as the convenience of daily inspection and fault maintenance, new requirements for high-voltage power supplies have emerged. Summary of the Invention

[0007] The purpose of this application is to overcome the problems in the prior art that the integrated high-voltage power supply is not convenient for maintenance and repair, and the operation stability and lifespan are easily affected by the outdoor operating environment due to the need to install all the integrated high-voltage power supplies outdoors close to the load equipment, and to provide a silicon carbide high-voltage power supply and its control method.

[0008] In a first aspect, a silicon carbide high-voltage power supply is provided, which includes a silicon carbide MOSFET inverter control module and a boost rectifier high-voltage module. The silicon carbide MOSFET inverter control module has a first module interconnecting interface, the boost rectifier high-voltage module has a second module interconnecting interface, and the first module interconnecting interface is electrically connected to the second module interconnecting interface through a detachable cable.

[0009] In some possible implementation manners, the silicon carbide MOSFET inverter control module includes a three-phase rectifier circuit and a controller. The input end of the three-phase rectifier circuit is connected to a first external interface through a circuit breaker. The output end of the three-phase rectifier circuit is connected in parallel with a filter circuit and a silicon carbide MOSFET inverter circuit. The three-phase rectifier circuit is also electrically connected to a monitoring interface, and the monitoring interface is electrically connected to the controller. The controller is also electrically connected to a human-machine interaction module and an inverter heat dissipation module. The output ends of the controller and the silicon carbide MOSFET inverter circuit are both electrically connected to a first module interconnection interface, and the controller is also connected to the first external interface. Specifically, the three-phase rectifier circuit includes diode one, diode two, diode three, diode four, diode five, and diode six. The silicon carbide MOSFET inverter circuit includes a first silicon carbide MOSFET, a second silicon carbide MOSFET, a third silicon carbide MOSFET, and a fourth silicon carbide MOSFET. The negative electrode of diode one is electrically connected to the positive electrode of diode two. The negative electrode of diode three is electrically connected to the positive electrode of diode four. The negative electrode of diode five is electrically connected to the positive electrode of diode six. The negative electrodes of diode one, diode three, and diode five are all connected to the first external interface through a circuit breaker. The positive electrodes of diode one, diode three, and diode five are all connected to the filter circuit, the source electrode of the third silicon carbide MOSFET, and the source electrode of the fourth silicon carbide MOSFET. The negative electrodes of diode two, diode four, and diode six are all connected to the monitoring interface, the filter circuit, the drain electrode of the first silicon carbide MOSFET, and the drain electrode of the second silicon carbide MOSFET. The gate electrodes of the second silicon carbide MOSFET and the third silicon carbide MOSFET are both connected to a first PWM drive signal through a conduction control level converter. The gate electrodes of the first silicon carbide MOSFET and the fourth silicon carbide MOSFET are both connected to a second PWM drive signal through a conduction control level converter. The source electrodes of the first silicon carbide MOSFET and the second silicon carbide MOSFET are both electrically connected to the first module interconnection interface. The controller is electrically connected to the monitoring interface, the first module interconnection interface, and the first external interface. The controller is electrically connected to a human-machine interaction module and an inverter heat dissipation module;

[0010] The minimum operating frequency of the silicon carbide MOSFET inverter circuit in the silicon carbide MOSFET inverter control module should satisfy the following formula:

[0011]

[0012] Where, F min is the minimum modulation AC frequency of the silicon carbide MOSFET inverter circuit; U p is the maximum voltage peak value of the AC voltage output by the silicon carbide MOSFET inverter circuit; N pN is the number of turns of the primary coil of the step-up transformer; △Bm is the change value of the maximum allowable magnetic density of the core material of the step-up transformer; S is the cross-sectional area of the core of the step-up transformer.

[0013] In some possible implementation manners, the first module interconnection interface includes a frequency and amplitude adjustable AC output interface, a high-voltage output voltage and current analog input interface, a transformer temperature analog input interface, and a transformer oil level digital input interface. The frequency and amplitude adjustable AC output interface is electrically connected to the silicon carbide MOSFET inverter circuit. Specifically, the frequency and amplitude adjustable AC output interface is electrically connected to the sources of the first silicon carbide MOSFET and the second silicon carbide MOSFET. The high-voltage output voltage and current analog input interface, the transformer temperature analog input interface, and the transformer oil level digital input interface are all electrically connected to the controller.

[0014] In some possible implementation manners, the first external interface includes a safety connection lock interface, a first grounding interface, a DCS distributed centralized control interface, a host computer monitoring system control interface, and a three-phase industrial frequency AC power supply interface. The safety connection lock interface, the first grounding interface, the DCS distributed centralized control interface, and the host computer monitoring system control interface are all electrically connected to the controller. The three-phase industrial frequency AC power supply interface is electrically connected to the circuit breaker. The safety connection lock interface is connected to the safety connection lock signal input interface through a cable, and an external safety interlock switch is electrically connected to the safety connection lock signal input interface.

[0015] In some possible implementation manners, high-voltage insulating oil is used for heat conduction inside the boost rectification high-voltage module, and the heat is conducted by the insulating oil to the radiating fins outside the heat dissipation oil tank of the boost rectification high-voltage module. The boost rectification high-voltage module includes a boost transformer, a temperature sensor, and an oil level sensor. The input coil of the boost transformer is connected in series with an inductor and then electrically connected to the second module interconnection interface. The output coil of the boost transformer is connected to a high-voltage rectification circuit. The high-voltage rectification circuit is connected to a second external interface through a sampling circuit. The high-voltage rectification circuit is also electrically connected to the second module interconnection interface through a sampling circuit. Both the temperature sensor and the oil level sensor are electrically connected to the second module interconnection interface. Specifically, the sampling circuit includes a first resistor, a second resistor, and a third resistor. The high-voltage rectification circuit includes diode eight, diode nine, diode ten, and diode eleven. The input coil of the boost transformer is connected in series with an inductor and then electrically connected to the second module interconnection interface. One end of the output coil of the boost transformer is electrically connected to the negative electrode of diode eight and the positive electrode of diode nine. The other end of the output coil of the boost transformer is electrically connected to the negative electrode of diode ten and the positive electrode of diode eleven. The positive electrodes of diode eight and diode ten are both electrically connected to one end of the third resistor and the second external interface. The negative electrodes of diode nine and diode eleven are both electrically connected to one end of the second resistor and the second module interconnection interface. The other end of the third resistor is electrically connected to one end of the first resistor. The other end of the third resistor is also electrically connected to the second module interconnection interface. The other ends of the second resistor and the first resistor are both electrically connected to the second module interconnection interface and the second external interface. Both the temperature sensor and the oil level sensor are electrically connected to the second module interconnection interface;

[0016] The primary coil of the boost transformer in the boost rectification high-voltage module is connected in series with an inductor L S , when the minimum modulation AC frequency of the silicon carbide MOSFET inverter circuit is at the minimum frequency F min , the following formula should be satisfied:

[0017]

[0018] U1 RMS is the maximum effective value of the input of the primary coil of the boost transformer in the boost rectification high-voltage module; F min is the minimum modulation AC frequency of the silicon carbide MOSFET inverter circuit; L S is the leakage inductance or the series inductance of the primary coil of the boost transformer in the boost rectification high-voltage module; N is the turns ratio of the boost transformer in the boost rectification high-voltage module; I2 RMS is the effective value of the high-voltage rated current output in the boost rectification high-voltage module.

[0019] In some possible implementation manners, the second module interconnection interface includes a transformer primary coil input interface, a high-voltage output voltage and current signal interface, a transformer temperature signal interface, and an oil level signal interface. Among them, the input coil of the step-up transformer is electrically connected to the transformer primary coil input interface in series with an inductor, the sampling circuit is electrically connected to the high-voltage output voltage and current signal interface. Specifically, the negative electrode of the diode nine and both ends of the first resistor are electrically connected to the high-voltage output voltage and current signal interface, the transformer temperature signal interface is electrically connected to a temperature sensor, the oil level signal interface is electrically connected to an oil level sensor, the temperature sensor and the oil level sensor are installed in the heat dissipation oil tank of the step-up rectification high-voltage module, the transformer primary coil input interface is electrically connected to the frequency and amplitude adjustable AC output interface through a detachable cable, the high-voltage output voltage and current signal interface is electrically connected to the high-voltage output voltage and current analog input interface through a detachable cable, the transformer temperature signal interface is electrically connected to the transformer temperature analog input interface through a detachable cable, and the oil level signal interface is electrically connected to the transformer oil level digital input interface through a detachable cable.

[0020] In some possible implementation manners, the second external interface includes a high-voltage interface and a second grounding interface. The high-voltage interface is electrically connected to the positive electrode of the diode eight, and the high-voltage interface and the second grounding interface are respectively electrically connected to both ends of the sampling circuit. Specifically, the second grounding interface is electrically connected to the end of the second resistor away from the diode nine.

[0021] Second aspect, a silicon carbide MOSFET inverter control module is provided, including a three-phase rectifier circuit and a controller. The input end of the three-phase rectifier circuit is connected to a first external interface through a circuit breaker. The output end of the three-phase rectifier circuit is connected in parallel with a filter circuit and a silicon carbide MOSFET inverter circuit. The three-phase rectifier circuit is also electrically connected to a monitoring interface, and the monitoring interface is electrically connected to the controller. The controller is also electrically connected to a human-machine interaction module and an inverter heat dissipation module. The output ends of the controller and the silicon carbide MOSFET inverter circuit are both electrically connected to a first module interconnection interface. The controller is also connected to the first external interface. Specifically, the three-phase rectifier circuit includes diode one, diode two, diode three, diode four, diode five and diode six. The silicon carbide MOSFET inverter circuit includes a first silicon carbide MOSFET, a second silicon carbide MOSFET, a third silicon carbide MOSFET and a fourth silicon carbide MOSFET. The negative electrode of diode one is electrically connected to the positive electrode of diode two. The negative electrode of diode three is electrically connected to the positive electrode of diode four. The negative electrode of diode five is electrically connected to the positive electrode of diode six. The negative electrodes of diode one, diode three and diode five are all connected to the first external interface through a circuit breaker. The positive electrodes of diode one, diode three and diode five are all connected to the filter circuit, the source electrode of the third silicon carbide MOSFET and the source electrode of the fourth silicon carbide MOSFET. The negative electrodes of diode two, diode four and diode six are all connected to the monitoring interface, the filter circuit, the drain electrode of the first silicon carbide MOSFET and the drain electrode of the second silicon carbide MOSFET. The gates of the second silicon carbide MOSFET and the third silicon carbide MOSFET are both connected to the first PWM driving signal through a conduction control level converter. The gates of the first silicon carbide MOSFET and the fourth silicon carbide MOSFET are both connected to the second PWM driving signal through a conduction control level converter. The source electrodes of the first silicon carbide MOSFET and the second silicon carbide MOSFET are both electrically connected to the first module interconnection interface. The controller is electrically connected to the monitoring interface, the first module interconnection interface and the first external interface. The controller is electrically connected to a human-machine interaction module and an inverter heat dissipation module.

[0022] In a third aspect, a step-up rectifier high-voltage module is provided, which includes a step-up transformer, a temperature sensor, and an oil level sensor. The input coil of the step-up transformer is connected in series with an inductor and then electrically connected to the second module interconnection interface. The output coil of the step-up transformer is connected to a high-voltage rectifier circuit. The high-voltage rectifier circuit is connected to a second external interface through a sampling circuit. The high-voltage rectifier circuit is also electrically connected to the second module interconnection interface through the sampling circuit. The temperature sensor and the oil level sensor are both electrically connected to the second module interconnection interface. Specifically, the sampling circuit includes a first resistor, a second resistor, and a third resistor. The high-voltage rectifier circuit includes diode eight, diode nine, diode ten, and diode eleven. The input coil of the step-up transformer is connected in series with an inductor and then electrically connected to the second module interconnection interface. One end of the output coil of the step-up transformer is electrically connected to the negative electrode of diode eight and the positive electrode of diode nine. The other end of the output coil of the step-up transformer is electrically connected to the negative electrode of diode ten and the positive electrode of diode eleven. The positive electrodes of diode eight and diode ten are both electrically connected to one end of the third resistor and the second external interface. The negative electrodes of diode nine and diode eleven are both electrically connected to one end of the second resistor and the second module interconnection interface. The other end of the third resistor is electrically connected to one end of the first resistor. The other end of the third resistor is also electrically connected to the second module interconnection interface. The other end of the second resistor and the other end of the first resistor are both electrically connected to the second module interconnection interface and the second external interface. The temperature sensor and the oil level sensor are both electrically connected to the second module interconnection interface.

[0023] In a fourth aspect, a control method for a silicon carbide high-voltage power supply is provided, which is used to control the silicon carbide high-voltage power supply as described in the first aspect above. The control method includes:

[0024] Controlling the pre-charge circuit of the filter circuit to pre-charge the filter circuit, and controlling the three-phase rectifier circuit to conduct when the pre-charge of the filter circuit is completed;

[0025] Judging whether a short circuit, a fault, or an external safety interlock switch is disconnected;

[0026] If the judgment result is yes, then disconnect the circuit breaker;

[0027] Controlling the silicon carbide MOSFET inverter circuit to invert direct current into alternating current with adjustable frequency and amplitude through the first PWM drive signal and the second PWM drive signal. Among them, the first PWM drive signal and the second PWM drive signal support two modes: unipolar SPWM modulation and bipolar SPWM modulation.

[0028] The present application has the following beneficial effects:

[0029] 1. The high-voltage power supply of this application is divided into two independent silicon carbide MOSFET inverter control modules and a boost rectifier high-voltage module, enabling the silicon carbide MOSFET inverter control module and the boost rectifier high-voltage module to be installed at different locations over a long distance through the first module interface and the second module interface. The silicon carbide MOSFET inverter control module in the low-voltage part can be installed near the indoor control room, which can improve the operating environment conditions of the silicon carbide MOSFET inverter control module, enhance the reliability and lifespan of the equipment, and is not easily affected by the outdoor environment. At the same time, it is convenient for control operations, inspections, maintenance, etc.; the boost rectifier high-voltage module in the high-voltage part is installed outdoors far away near the load equipment, which is convenient for high-voltage connection with the load equipment, avoiding high-voltage safety hazards. At the same time, the modular design can also simplify the manufacturing process flow and facilitate standardized production.

[0030] 2. The inverter circuit of the silicon carbide MOSFET inverter control module of this application takes the silicon carbide MOSFET as the core, which can increase the operating frequency of the inverter circuit, thereby increasing the frequency of the modulated AC output of the inverter. The increase in the frequency of the AC output can greatly reduce the weight, volume, and manufacturing cost of the boost rectifier high-voltage module, and at the same time reduce the switching loss of the power inverter circuit, improving the efficiency of the high-voltage power supply.

[0031] 3. The high-voltage power supply of this application can achieve local human-machine operation, control by the upper computer monitoring system, and DC distributed centralized control by setting a human-machine interaction module, a DCS distributed centralized control interface, and an upper computer monitoring system control interface. And by setting a safety connection lock interface, a safety connection lock signal input interface, and an external safety interlock switch, the circuit breaker can be automatically disconnected before danger occurs through the switch signal of the external safety interlock switch, completely disconnecting the high-voltage power supply.

[0032] 4. The silicon carbide MOSFET inverter control module and the boost rectifier high-voltage module of this application are two independent and separate modules. The silicon carbide MOSFET inverter control module and the boost rectifier high-voltage module can be sold as independent products and purchased according to needs during maintenance. At the same time, the silicon carbide MOSFET inverter control module can also be used as an independent product to transform and upgrade high-voltage power supply equipment controlled by thyristors.

[0033] 5. The first PWM drive signal and the second PWM drive signal of this application support two mode selections of unipolar SPWM modulation and bipolar SPWM modulation, which can be adapted to the combined silicon carbide MOSFET device with an anti-parallel silicon carbide diode and the pure silicon carbide MOSFET device without an anti-parallel silicon carbide diode, further supporting the linear AC modulation and non-linear AC modulation of the high-voltage power supply output, being applicable to different load characteristics, and realizing the energy-saving and optimized control output of the high-voltage power supply. Description of the Drawings

[0034] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application.

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic structural diagram of a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0037] Figure 2 It is a circuit diagram of a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0038] Figure 3 It is a unipolar SPWM modulation waveform diagram of a silicon carbide MOSFET inverter circuit in a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0039] Figure 4 It is a bipolar SPWM modulation waveform diagram of a silicon carbide MOSFET inverter circuit in a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0040] Figure 5 It is an output waveform diagram of a high-voltage power supply with linear AC modulation control of a silicon carbide MOSFET inverter circuit in a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0041] Figure 6 It is an output waveform diagram of a high-voltage power supply with non-linear AC modulation control of a silicon carbide MOSFET inverter circuit in a silicon carbide high-voltage power supply according to Embodiment 1 of this application;

[0042] Figure 7 It is a circuit diagram of a silicon carbide MOSFET inverter control module according to Embodiment 2 of this application;

[0043] Figure 8 It is a circuit diagram of a boost rectifier high-voltage module according to Embodiment 3 of this application;

[0044] Figure 9 It is a flowchart of a control method for a silicon carbide high-voltage power supply according to Embodiment 4 of this application.

[0045] Reference numerals:

[0046] 100, silicon carbide MOSFET inverter control module; 200, boost rectifier high-voltage module; 300, first module interconnecting interface; 400, second module interconnecting interface; 500, cable. Detailed implementation manners

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Embodiment 1

[0049] As Figure 1 shown, a silicon carbide high-voltage power supply involved in Embodiment 1 of the present application includes two independent and separated modules, namely a silicon carbide MOSFET inverter control module 100 and a boost rectifier high-voltage module 200. The silicon carbide MOSFET inverter control module 100 has a first module interconnecting interface 300, and the boost rectifier high-voltage module 200 has a second module interconnecting interface 400. The first module interconnecting interface 300 is electrically connected to the second module interconnecting interface 400 through a detachable cable 500. The silicon carbide MOSFET inverter control module 100 and the boost rectifier high-voltage module 200 can be installed at different positions with a relatively long isolation distance, and the complete control function of the silicon carbide high-voltage power supply can be maintained, which can improve the operating environmental conditions of the silicon carbide MOSFET inverter control module 100, enhance the reliability and service life of the equipment, and is not easily affected by the outdoor environment. At the same time, it is convenient for control operation, inspection, maintenance, etc.; for the boost rectifier high-voltage module 200 in the high-voltage part, it is installed near the load equipment outdoors at a distance, which is convenient for high-voltage connection with the load equipment, avoiding high-voltage safety hazards. At the same time, the modular design can also simplify the manufacturing process flow and facilitate standardized production.

[0050] For the two independent and separated modules, the silicon carbide MOSFET inverter control module 100 in the low-voltage part is installed nearby in the indoor control room, which can improve the operating environmental conditions of the silicon carbide MOSFET inverter control module 100, enhance the reliability and service life of the equipment, and is convenient for control operation, inspection, maintenance, etc. For the boost rectifier high-voltage module 200 in the high-voltage part, it is installed near the load equipment outdoors at a distance, which is convenient for high-voltage connection with the load and avoids high-voltage safety hazards.

[0051] Among them, the silicon carbide MOSFET inverter control module 100 consists of a circuit breaker, a three-phase rectifier circuit, a filter circuit, a silicon carbide MOSFET inverter circuit, an inverter heat dissipation module, a controller A1 with an embedded control system, a human-machine interaction module HMI, a first module interconnection interface 300, and a first external interface. The first module interconnection interface 300 includes an analog input interface for high-voltage output voltage, an analog input interface for high-voltage output current, an analog input interface for transformer temperature, a digital input interface for transformer oil level switch, and a frequency and amplitude adjustable AC output interface. The silicon carbide MOSFET inverter circuit dissipates heat through the inverter heat dissipation module using a liquid cooling circulation cooling method.

[0052] The silicon carbide MOSFET inverter control module 100 adopts a cabinet design. The height of the cabinet is between 1.8 m and 2.5 m, the width is between 600 mm and 800 mm, and the depth is between 600 mm and 800 mm.

[0053] Among them, the boost rectifier high-voltage module 200 consists of a boost transformer, a series inductor in the primary coil (i.e., input coil) of the boost transformer (note: it can be the leakage inductance of the boost transformer itself), a high-voltage rectifier circuit, a sampling circuit, an oil level sensor, a temperature sensor, a second module interconnection interface 400, and a second external interface. The second module interconnection interface 400 includes a high-voltage output voltage signal interface, a high-voltage output current signal interface, a transformer temperature signal interface, an oil level signal interface, and a transformer primary coil input interface. The boost rectifier high-voltage module 200 uses high-voltage insulating oil for heat conduction inside. The heat is conducted by the insulating oil to the radiator outside the oil tank of the boost rectifier high-voltage module 200, and natural cooling is achieved through the exchange of the radiator outside the oil tank with the air.

[0054] The maximum rated output voltage average value range of the boost rectifier high-voltage module 200 is 40 kV - 200 kV, and it supports full-range output regulation from 0 to the rated voltage for high voltage.

[0055] The first module interconnection interface 300 in the silicon carbide MOSFET inverter control module 100 is connected to the second module interconnection interface 400 in the boost rectifier high-voltage module 200 through a cable 500, and the length of the cable 500 is not greater than 1000 meters.

[0056] The silicon carbide MOSFET inverter circuit, with silicon carbide MOSFET semiconductor switching devices as the core, is under the closed-loop control of the embedded control system. The carrier frequency of the inverter circuit is 10 k - 20 kHZ. Based on the carrier frequency, the DC is inverted and modulated into an alternating current with an adjustable frequency range of 50 - 1000 HZ and an adjustable voltage amplitude range of 0 - 2048 levels.

[0057] The minimum operating frequency of the boost transformer in the boost rectifier high-voltage module 200 is related to the volume and weight of the transformer. The higher the frequency, the smaller the volume and weight of the transformer, and the lower the frequency, the larger the volume and weight of the transformer. New transformers are generally designed to match the silicon carbide inverter circuit at a higher frequency, but there are still many 50HZ power frequency transformers in the market. To be compatible with 50HZ power frequency transformers, the lower limit of the adjustable frequency range is set at 50HZ. The core cross-section of a 1000HZ transformer can be reduced by 20 times compared to that of a 50HZ transformer.

[0058] The minimum operating frequency F of the silicon carbide MOSFET inverter circuit min is related to the number of turns of the coil and the core of the boost transformer in the boost rectifier high-voltage module 200. The minimum operating frequency F of the silicon carbide MOSFET inverter circuit min should satisfy the following formula:

[0059]

[0060] F min is the minimum modulation AC frequency of the silicon carbide MOSFET inverter circuit; U p is the maximum voltage peak value of the AC voltage output of the silicon carbide MOSFET inverter circuit; N p is the number of turns of the primary coil of the boost transformer; △Bm is the change value of the maximum allowable magnetic density of the core material of the boost transformer; S is the cross-sectional area of the core of the boost transformer.

[0061] The current of the silicon carbide MOSFET device in the silicon carbide MOSFET inverter circuit should simultaneously satisfy the following formula:

[0062] ;

[0063] and .

[0064] Among them, IDM is the drain peak current of the silicon carbide MOSFET device, U1 RMS is the maximum input effective value of the primary coil of the boost transformer in the boost rectifier high-voltage module 200, F min is the minimum allowable operating frequency of the boost transformer in the boost rectifier high-voltage module 200, and LS is the leakage inductance or series inductance of the primary coil of the boost transformer in the boost rectifier high-voltage module 200.

[0065] ID is the drain rated current value of the silicon carbide MOSFET device; U1 RMS is the maximum input effective value of the primary coil of the boost transformer in the boost rectifier high-voltage module 200; U2AV is the average value of the high-voltage rated voltage output in the boost rectifier high-voltage module 200, and I2AV is the average value of the high-voltage rated current output in the boost rectifier high-voltage module 200.

[0066] In order to limit the impact on the SiC MOSFET device when the high-voltage output of the SiC high-voltage power supply is short-circuited, an inductance L is connected in series with the primary coil of the step-up transformer in the step-up rectifier high-voltage module 200 S (Note: It can be the leakage inductance of the step-up transformer itself). When the minimum modulation AC frequency of the SiC MOSFET inverter circuit is at the minimum frequency F min , the following formula should be satisfied:

[0067]

[0068] U1 RMS is the maximum effective value of the input of the primary coil of the step-up transformer in the step-up rectifier high-voltage module 200; F min is the minimum modulation AC frequency of the SiC MOSFET inverter circuit; L S is the leakage inductance or the series inductance of the primary coil of the step-up transformer in the step-up rectifier high-voltage module 200; N is the turns ratio of the step-up transformer in the step-up rectifier high-voltage module 200; I2 RMS is the effective value of the high-voltage rated current output in the step-up rectifier high-voltage module 200

[0069] The embedded control system of the SiC MOSFET inverter control module 100 controls the SiC MOSFET inverter circuit through two drive signals. The drive signals support two mode selections of unipolar SPWM modulation and bipolar SPWM modulation, and can be adapted to the combined SiC MOSFET device with an anti-parallel SiC diode and the pure SiC MOSFET device without an anti-parallel SiC diode. Further, it supports the linear AC modulation and non-linear AC modulation of the high-voltage power supply output, realizes adaptation to different load characteristics, and realizes the energy-saving optimization control output of the high-voltage power supply. The non-linear AC modulation consists of a modulation unit time period composed of T1 time and T2 time. T1 time controls the peak value of the high-voltage power supply output voltage, and T2 time controls the valley value of the high-voltage power supply output voltage, repeating cyclically, and T1 time and T2 time are respectively integer multiples of half of the AC change period generated by the inverter

[0070] The embedded control system of the SiC MOSFET inverter control module 100 supports on-site human-machine operation, host computer monitoring system control, and DCS distributed centralized control at the same time

[0071] The safety connection lock interface of the SiC MOSFET inverter control module 100 is equipped with a safety interlock protection mechanism, which can disconnect the distribution circuit breaker of the high-voltage power supply before danger occurs and completely cut off the high-voltage power supply

[0072] Such as Figure 2As shown, the silicon carbide high-voltage power supply includes two independent and separated modules: the silicon carbide MOSFET inverter control module 100 and the boost rectifier high-voltage module 200. The silicon carbide MOSFET inverter control module 100 includes a circuit breaker QF1, a three-phase rectifier circuit ZD1 (the three-phase rectifier circuit includes diode D1, diode D2, diode D3, diode D4, diode D5, and diode D6), a filter circuit C1, a silicon carbide MOSFET inverter circuit, an inverter heat dissipation module COOLING SYSTEM, a controller A1 with an embedded control system, a human-machine interaction module HMI, and a first external interface. The silicon carbide MOSFET inverter circuit includes a first silicon carbide MOSFET VT1, a second silicon carbide MOSFET VT2, a third silicon carbide MOSFET VT3, and a fourth silicon carbide MOSFET VT4. The negative electrode of diode D1 is electrically connected to the positive electrode of diode D2. The negative electrode of diode D3 is electrically connected to the positive electrode of diode D4. The negative electrode of diode D5 is electrically connected to the positive electrode of diode D6. The negative electrodes of diode D1, diode D3, and diode D5 are all connected to the first external interface through the circuit breaker QF1. The positive electrodes of diode D1, diode D3, and diode D5 are all connected to the filter circuit C1, the source electrode of the third silicon carbide MOSFET VT3, and the source electrode of the fourth silicon carbide MOSFET VT4. The negative electrodes of diode D2, diode D4, and diode D6 are all connected to the monitoring interface QD1, the filter circuit C1, the drain electrode of the first silicon carbide MOSFET VT1, and the drain electrode of the second silicon carbide MOSFET VT2. The gate electrodes of the second silicon carbide MOSFET VT2 and the third silicon carbide MOSFET VT3 are both connected to the first PWM drive signal PWM1 through a conduction control level converter. The gate electrodes of the first silicon carbide MOSFET VT1 and the fourth silicon carbide MOSFET VT4 are both connected to the second PWM drive signal PWM2 through a conduction control level converter. The source electrodes of the first silicon carbide MOSFET VT1 and the second silicon carbide MOSFET VT2 are both electrically connected to the first module interconnection interface 300. The controller A1 is electrically connected to the monitoring interface QD1, the first module interconnection interface 300, and the first external interface. The controller A1 is electrically connected to the human-machine interaction module HMI and the inverter heat dissipation module COOLING SYSTEM. The embedded control system controls the three-phase rectifier circuit ZD1 through the monitoring interface QD1, and can realize the monitoring of the rectified DC voltage, pre-charge control, etc. The inverter circuit of the silicon carbide MOSFET inverter control module 100 takes the silicon carbide MOSFET as the core, which can increase the operating frequency of the inverter circuit, thereby increasing the frequency of the modulated AC output of the inverter. The increase in the frequency of the AC output can greatly reduce the weight, volume, and manufacturing cost of the boost rectifier high-voltage module 200, and at the same time reduce the switching loss of the power inverter circuit.It can improve the efficiency of the high-voltage power supply.

[0073] The silicon carbide MOSFET inverter circuit dissipates heat through a liquid cooling circulation cooling method by the inverter heat dissipation module COOLING SYSTEM. The embedded control system controls the inverter heat dissipation module COOLING SYSTEM through the CS1 interface of the controller A1.

[0074] The first module interconnection interface 300 includes a frequency and amplitude adjustable AC output interface J11, a high-voltage output voltage and current analog input interface J12, a transformer temperature analog input interface J13, and a transformer oil level digital input interface J14. The frequency and amplitude adjustable AC output interface J11 is electrically connected to the sources of the first silicon carbide MOSFET VT1 and the second silicon carbide MOSFET VT2. The high-voltage output voltage and current analog input interface J12, the transformer temperature analog input interface J13, and the transformer oil level digital input interface J14 are all electrically connected to the controller A1.

[0075] The first external interface includes a safety connection lock interface W11, a first grounding interface W12, a DCS distributed centralized control interface W13, a host computer monitoring system control interface W14, and a three-phase power frequency AC power supply interface W15. The safety connection lock interface W11, the first grounding interface W12, the DCS distributed centralized control interface W13, and the host computer monitoring system control interface W14 are all electrically connected to the controller A1. The three-phase power frequency AC power supply interface W15 is electrically connected to the circuit breaker QF1. The safety connection lock interface W11 is connected to the safety connection lock signal input interface through a cable 500. The safety connection lock signal input interface is electrically connected to an external safety interlock switch K2. Among them, the safety connection lock interface W11 is used to connect the external safety interlock switch K2, the first grounding interface W12 is used for grounding, the DCS distributed centralized control interface W13 is used to access the DCS distributed centralized control signal, the host computer monitoring system control interface W14 is used to access the control signal of the host computer monitoring system, and the three-phase power frequency AC power supply interface W15 is used to access the A, B, and C three-phase power frequency AC power supply. By setting the human-machine interaction module, the DCS distributed centralized control interface, and the host computer monitoring system control interface, on-site human-machine operation, host computer monitoring system control, and DC distributed centralized control can be realized. And by setting the safety connection lock interface, the safety connection lock signal input interface, and the external safety interlock switch, the circuit breaker can be automatically disconnected before danger occurs through the switch signal of the external safety interlock switch, completely disconnecting the high-voltage power supply.

[0076] Such as Figure 2As shown, the step-up rectifier high-voltage module 200 uses insulating heat-conducting oil for heat conduction inside. The heat is conducted by the insulating heat-conducting oil to the heat sink outside the fuel tank of the step-up rectifier high-voltage module 200, and natural cooling is achieved through the heat exchange between the heat sink outside the fuel tank and the air. The step-up rectifier high-voltage module 200 includes a step-up transformer TR1, an inductor Ls, a high-voltage rectifier circuit ZD2, a sampling circuit, a temperature sensor 2PT100, an oil level sensor K1, and a second external interface. Among them, the sampling circuit includes a first resistor R21, a second resistor R22, and a third resistor R23. The high-voltage rectifier circuit ZD2 includes a diode eight D8, a diode nine D9, a diode ten D10, and a diode eleven D11. The input coil of the step-up transformer TR1 is connected in series with the inductor Ls and then electrically connected to the second module interconnection interface 400. One end of the output coil of the step-up transformer TR1 is electrically connected to the negative electrode of the diode eight D8 and the positive electrode of the diode nine D9. The other end of the output coil of the step-up transformer TR1 is electrically connected to the negative electrode of the diode ten D10 and the positive electrode of the diode eleven D11. The positive electrodes of the diode eight D8 and the diode ten D10 are both electrically connected to one end of the third resistor R23 and the second external interface. The negative electrodes of the diode nine D9 and the diode eleven D11 are both electrically connected to one end of the second resistor R22 and the second module interconnection interface 400. The other end of the third resistor R23 is electrically connected to one end of the first resistor R21. The other end of the third resistor R23 is also electrically connected to the second module interconnection interface 400. The other ends of the second resistor R22 and the first resistor R21 are both electrically connected to the second module interconnection interface 400 and the second external interface. The temperature sensor 2PT100 and the oil level sensor K1 are both electrically connected to the second module interconnection interface 400.

[0077] The second module interconnection interface 400 includes a transformer primary coil input interface J21, a high-voltage output voltage and current signal interface J22, a transformer temperature signal interface J23, and an oil level signal interface J24. Among them, the input coil of the step-up transformer TR1 is connected in series with an inductor Ls and electrically connected to the transformer primary coil input interface J21. The negative electrode of the diode D9 and both ends of the first resistor R21 are electrically connected to the high-voltage output voltage and current signal interface J22. The transformer temperature signal interface J23 is electrically connected to the temperature sensor 2PT100, and the oil level signal interface J24 is electrically connected to the oil level sensor K1. The temperature sensor 2PT100 and the oil level sensor K1 are installed in the fuel tank. The transformer primary coil input interface J21 is electrically connected to the frequency and amplitude adjustable AC output interface J11 through a detachable cable 500. The high-voltage output voltage and current signal interface J22 is electrically connected to the high-voltage output voltage and current analog input interface J12 through a detachable cable 500. The transformer temperature signal interface J23 is electrically connected to the transformer temperature analog input interface J13 through a detachable cable 500. The oil level signal interface J24 is electrically connected to the transformer oil level digital input interface J14 through a detachable cable 500.

[0078] The second external interface includes a high-voltage interface W21 and a second grounding interface W22. The high-voltage interface W21 is electrically connected to the positive electrode of the diode D8, and the second grounding interface W22 is electrically connected to one end of the second resistor R22 away from the diode D9.

[0079] The silicon carbide MOSFET inverter control module 100 connects the three-phase industrial frequency AC power supply of phases A, B, and C to the three-phase circuit breaker QF1 through the three-phase industrial frequency AC power supply interface W15. The first main function of the circuit breaker QF1 is to achieve short-circuit protection of the power supply through its own short-circuit protection function. The second main function of the circuit breaker QF1 is that the embedded control system collects and monitors the signals related to the external power supply, and triggers fault protection according to the fault conditions inside the software of the embedded control system. When a fault occurs, the QF1 fault interface of the embedded control system controls the tripping coil of the circuit breaker QF1 to trigger the circuit breaker QF1 to perform fault tripping protection. The third main function of the circuit breaker QF1 is that K2 is an external safety interlock switch. The external safety interlock switch K2 is connected to the safety connection lock interface W11 through the signal cable WR5. When the external safety interlock switch K2 is disconnected, the circuit breaker QF1 of the high-voltage power supply can be disconnected before danger occurs, completely disconnecting the high-voltage power supply. The application description of the external safety interlock switch K2 is not limited to this: The external safety interlock switch K2 can be set on the door of the safety protection fence around the boost rectifier high-voltage module 200. During high-voltage operation, when someone tries to open the door of the safety protection fence, the circuit breaker QF1 of the high-voltage power supply can be disconnected before dangerous electric shock occurs, completely disconnecting the high-voltage power supply.

[0080] After the three-phase alternating current passes through the circuit breaker QF1, it enters the three-phase rectifier circuit ZD1 to convert the alternating current into direct current. The QD1 interface of the embedded control system collects the DC voltage of the three-phase rectifier circuit ZD1 and controls the pre-charge circuit of the filter circuit C1 to pre-charge the filter circuit C1, restricting and reducing the current of the zero-voltage charging of the filter circuit C1 during the initial power-on, and reducing interference. When the charging is completed, the thyristor trigger signal of the three-phase rectifier circuit ZD1 is controlled at the same time to control the conduction of the three-phase rectifier circuit ZD1.

[0081] After being filtered by the filter circuit C1, the direct current powers the silicon carbide MOSFET inverter circuit VT1-VT4. The silicon carbide MOSFET inverter circuit VT1-VT4 is controlled by the first PWM drive signal PWM1 and the second PWM drive signal PWM2 of the embedded control system to invert the direct current into an alternating current with adjustable frequency and amplitude. The alternating current with adjustable frequency and amplitude is connected to the input interface J21 of the primary coil of the transformer in the boost rectifier high-voltage module 200 through the power cable WR1 via the frequency and amplitude adjustable AC output interface J11. Thus, it is realized to control the silicon carbide MOSFET inverter circuit VT1-VT4 through the first PWM drive signal PWM1 and the second PWM drive signal PWM2 to change the output voltage and current of the boost rectifier high-voltage module 200.

[0082] In the boost rectifier high-voltage module 200, the boost transformer TR1 boosts the AC power with adjustable frequency and amplitude. After boosting, it is rectified by the high-voltage rectifier circuit ZD2. One end of the high voltage output by the high-voltage rectifier circuit ZD2 is connected to the high-voltage interface W21 through a high-voltage porcelain insulator. After the high-voltage interface W21 is connected in series with the current-limiting resistor R24, it is connected to the high-voltage input end of the load Z1. The other end of the DC output of the high-voltage rectifier circuit ZD2 is connected to the second resistor R22 for high-voltage output current sampling, and then grounded through the second grounding interface W22 and connected to the grounding point of the load Z1. One end of the high voltage output by the high-voltage rectifier circuit ZD2 is also connected to the third resistor R23 for high-voltage output voltage sampling. The third resistor R23 is connected in series with the first resistor R21, and the other end of the first resistor R21 is connected to the second resistor R22 and grounded through the second grounding interface W22.

[0083] In the boost rectifier high-voltage module 200, the high-voltage output voltage and current signal interface J22 is connected to the high-voltage output voltage and current analog input interface J12 in the silicon carbide MOSFET inverter control module 100 through the signal shielded cable WR2, and finally enters the embedded control system.

[0084] In the boost rectifier high-voltage module 200, the transformer temperature signal interface J23 is connected to the transformer temperature analog input interface J13 in the silicon carbide MOSFET inverter control module 100 through the signal shielded cable WR3, and finally enters the embedded control system.

[0085] In the boost rectifier high-voltage module 200, the oil level signal interface J24 is connected to the transformer oil level digital input interface J14 in the silicon carbide MOSFET inverter control module 100 through the signal cable WR3, and finally enters the embedded control system.

[0086] The external safety interlock signal of the external safety interlock switch K2 is connected to the safety connection lock interface W11 in the silicon carbide MOSFET inverter control module 100 through the signal cable WR5, and finally enters the embedded control system.

[0087] The PWM1 and PWM2 drive signals of the embedded control system support two modes: unipolar SPWM modulation and bipolar SPWM modulation. The unipolar SPWM modulation is as Figure 3 shown, and the bipolar SPWM modulation is as Figure 4 shown.

[0088] In practical applications, there are two types of semiconductor modules for silicon carbide MOSFET devices. One is a pure silicon carbide MOSFET device, which only contains MOSFET transistors in the module and has no anti-parallel silicon carbide diode externally. The inverter circuit relies on the body diode of the MOSFET transistor for freewheeling. However, due to the high forward voltage conduction voltage drop of the body diode of the MOSFET transistor itself, reaching 5 - 6V, the freewheeling loss is relatively large. Since there is no anti-parallel silicon carbide diode externally, the loss of the inverter circuit is relatively large, but the module cost is relatively low. The other is a combined silicon carbide MOSFET device with an externally anti-parallel silicon carbide diode. The forward voltage conduction voltage drop of the anti-parallel silicon carbide diode is relatively low, generally 1 - 2V, and the loss is small. Due to the presence of an externally anti-parallel silicon carbide diode, the loss of the inverter circuit is small and the efficiency is high, but the module cost is high.

[0089] When using a pure silicon carbide MOSFET device without an anti-parallel silicon carbide diode for the inverter circuit, the PWM1 and PWM2 drive signals of the embedded control system adopt bipolar SPWM modulation. Figure 4 In this case, the modulation wave AC1 is compared with the bipolar triangular carrier wave VSAN to complementarily output the PWM1 and PWM2 drive signals. During the positive half-wave period of the modulation wave AC1, the PWM1 drive signal mainly drives the inverter circuit VT2 and VT3, and the PWM2 drive signal is used to complementarily drive the inverter circuit VT1 and VT4. The PWM2 drive signal drives VT1 and VT4 to provide freewheeling, which is used to reduce the forward conduction loss of the body diode of the silicon carbide MOSFET for freewheeling. During the negative half-wave period of the modulation wave AC1, the PWM2 drive signal mainly drives the inverter circuit VT1 and VT4, and the PWM1 drive signal is used to complementarily drive the inverter circuit VT2 and VT3. The PWM1 drive signal drives VT2 and VT3 to provide freewheeling, which is used to reduce the forward conduction loss of the body diode of the silicon carbide MOSFET for freewheeling.

[0090] When using a combined silicon carbide MOSFET device with an anti-parallel silicon carbide diode for the inverter circuit, the PWM1 and PWM2 drive signals of the embedded control system adopt unipolar SPWM modulation. Figure 3 In this case, the modulation wave AC1 is compared with the unipolar triangular carrier wave VSAN. When the PWM1 and PWM2 drive signals work in one path, the other drive signal stops output, which can effectively reduce the switching loss of the inverter circuit. At the same time, there is no need to consider the dead time for PWM1 and PWM2, and the reliability is relatively high. During the positive half-wave period of the modulation wave AC1, the PWM1 drive signal works to drive the inverter circuit VT2 and VT3, and the PWM2 drive signal stops. The circuit freewheels through the anti-parallel silicon carbide diode. During the negative half-wave period of the modulation wave AC1, the PWM2 drive signal drives the inverter circuit VT1 and VT4, and the PWM1 drive signal stops. The PWM1 circuit freewheels through the anti-parallel silicon carbide diode.

[0091] The PWM1 and PWM2 drive signals of the embedded control system support two modes: unipolar SPWM modulation and bipolar SPWM modulation. They can be applied to different silicon carbide MOSFET devices and maximize the performance of different silicon carbide MOSFET devices.

[0092] Based on the fact that the PWM1 and PWM2 drive signals of the embedded control system support unipolar SPWM modulation and bipolar SPWM modulation, it further optimizes to support linear AC modulation and non-linear AC modulation to achieve energy-saving and optimized output of the high-voltage power supply.

[0093] The linear AC modulation of the silicon carbide MOSFET inverter circuit controls the high-voltage power supply, such as Figure 5 shown:

[0094] Figure 5 In it, the modulation wave AC1 is compared with the bipolar triangular carrier wave VSAN, and the complementary output PWM1 and PWM2 drive signals. The peak value and frequency of the modulation wave AC1 sine signal remain unchanged within one unit time period. In each next unit time period, the peak value of the modulation wave AC1 sine signal slowly changes (increases or decreases) to control the output of the high-voltage power supply. The DC ripple coefficient of the output of the high-voltage power supply U2 within one unit time period is very small, approaching the change of direct current, and it can be applied to occasions where the load requires a stable output of the high-voltage power supply. By controlling the peak voltage magnitude of the modulation wave AC1 sine signal, the high-voltage power supply can achieve stable output at any voltage value within the range from zero to the rated output voltage. Figure 5 In it, the modulation wave AC1 with a peak voltage of P1 slowly increases to the modulation wave AC2 with a peak voltage of P2, which can control the output of the high-voltage power supply U2 to increase from the DC average voltage of 29 KV to the DC average voltage of 79 KV.

[0095] The non-linear AC modulation of the silicon carbide MOSFET inverter circuit controls the high-voltage power supply, such as Figure 6 shown:

[0096] Figure 6 In it, the modulation wave AC1 is compared with the bipolar triangular carrier wave VSAN, and the complementary output PWM1 and PWM2 drive signals. The peak voltage of the modulation wave AC1 sine signal changes significantly within one unit time period, and the output voltage value of the high-voltage power supply U2 changes significantly within one unit time period. It can be applied to occasions where energy-saving and optimized control are required due to changes in the load conditions. Figure 6Among them, T1 and T2 form a modulation unit time period. During T1, the voltage value of the peak voltage Pa of the modulated wave AC1 sine signal is large, and the high-voltage power supply U2 is controlled to output and rise to the peak DC voltage Up. During T2, the voltage value of the peak voltage Pb of the modulated wave AC1 sine signal is small, and the high-voltage power supply U2 is controlled to output and drop to the valley DC voltage Uv. The cycle of the sine signal of the modulated wave AC1 repeats within T1 and T2, and the cycle of the output voltage peak Up and the voltage valley Uv of the high-voltage power supply U2 repeats, presenting the effect of DC superimposed pulses.

[0097] Typical application of a high-voltage power supply controlled by non-linear AC modulation of a silicon carbide MOSFET inverter circuit:

[0098] A coal-fired power generation unit is used for power grid power supply peak shaving in a new energy system. Under deep peak shaving conditions, the load of the coal-fired power generation unit is adjusted in the range of 30% - 100%. At this time, the flue gas volume generated by the boiler of the coal-fired power generation unit changes in the range of 30% - 100%, and the flue gas flow rate entering the electric precipitator electric field changes in the range of 30% - 100%. When the coal-fired generator is at 100% load, assuming the flue gas flow rate is 1 m / s, and at 30% load, the flue gas flow rate is 0.3 m / s. When the coal-fired generator is at 100% load, the dust is discharged up to the standard, and the electric precipitator is designed and configured. The electric precipitator has five electric fields, and the total length of the electric fields is 25 meters. When the load changes in the range of 30% - 100%, the flue gas flow rate changes from 0.3 m / s to 1 m / s, and the flue gas moving speed per millisecond is 0.3 mm - 1 mm. The residence time of the flue gas with a total electric field length of 25 meters is 83 s - 25 s. The non-linear AC modulation T1 and T2 modulation periods of the silicon carbide MOSFET inverter circuit can be adjusted according to the residence time of the flue gas after the load changes, and precise energy-saving control of the high-voltage power supply can be achieved while taking into account environmental protection and up-to-standard emissions. During T1, the peak value of the modulated wave sine signal is high, and the PWM1 and PWM2 drive signals control the high-voltage power supply to output a high peak voltage, causing the load to generate high-concentration positive and negative ions, enabling the dust in the area covered by the discharge electrode to be quickly charged. After the dust is charged, the T2 time is adjusted according to the residence time of the flue gas, and the power output of the high-voltage power supply is reduced. The peak value of the modulated wave sine signal during T2 is small, and the PWM1 and PWM2 drive signals control the high-voltage power supply to output a low peak voltage, maintaining a certain electric field strength and the driving force for the charged dust, thus achieving energy-saving control.

[0099] Example 2

[0100] Such as Figure 7As shown in the figure, a silicon carbide MOSFET inverter control module involved in Embodiment 2 of the present application includes a circuit breaker QF1, a three-phase rectifier circuit ZD1 (the three-phase rectifier circuit includes diode D1, diode D2, diode D3, diode D4, diode D5, and diode D6), a filter circuit C1, a silicon carbide MOSFET inverter circuit, an inverter heat dissipation module COOLING SYSTEM, a controller A1 with an embedded control system, a human-machine interaction module HMI, and a first external interface. The silicon carbide MOSFET inverter circuit includes a first silicon carbide MOSFET VT1, a second silicon carbide MOSFET VT2, a third silicon carbide MOSFET VT3, and a fourth silicon carbide MOSFET VT4. The negative electrode of diode D1 is electrically connected to the positive electrode of diode D2. The negative electrode of diode D3 is electrically connected to the positive electrode of diode D4. The negative electrode of diode D5 is electrically connected to the positive electrode of diode D6. The negative electrodes of diode D1, diode D3, and diode D5 are all connected to the first external interface through circuit breaker QF1. The positive electrodes of diode D1, diode D3, and diode D5 are all connected to the filter circuit C1, the source electrode of the third silicon carbide MOSFET VT3, and the source electrode of the fourth silicon carbide MOSFET VT4. The negative electrodes of diode D2, diode D4, and diode D6 are all connected to the monitoring interface QD1, the filter circuit C1, the drain electrode of the first silicon carbide MOSFET VT1, and the drain electrode of the second silicon carbide MOSFET VT2. The gate electrodes of the second silicon carbide MOSFET VT2 and the third silicon carbide MOSFET VT3 are both connected to the first PWM drive signal PWM1 through a conduction control level converter. The gate electrodes of the first silicon carbide MOSFET VT1 and the fourth silicon carbide MOSFET VT4 are both connected to the second PWM drive signal PWM2 through a conduction control level converter. The source electrodes of the first silicon carbide MOSFET VT1 and the second silicon carbide MOSFET VT2 are both electrically connected to the first module interconnection interface 300. The controller A1 is electrically connected to the monitoring interface QD1, the first module interconnection interface 300, and the first external interface. The controller A1 is electrically connected to the human-machine interaction module HMI and the inverter heat dissipation module COOLING SYSTEM. The silicon carbide MOSFET inverter control module 100 is an independent and separated module. The silicon carbide MOSFET inverter control module 100 can be sold as an independent product and can be purchased according to needs during maintenance. At the same time, the silicon carbide MOSFET inverter control module 100 can also be used as an independent product to transform and upgrade equipment such as high-voltage power supplies controlled by thyristors.

[0101] It should be noted that for other specific implementation manners of the control method of the silicon carbide high-voltage power supply in this embodiment, reference can be made to the specific implementation manner of the above-mentioned silicon carbide high-voltage power supply. To avoid redundancy, it will not be elaborated here.

[0102] Example 3

[0103] As Figure 8 shown, a boost rectifier high-voltage module involved in Embodiment 3 of the present application uses insulating heat-conducting oil for heat conduction inside the boost rectifier high-voltage module 200. The heat is conducted by the insulating heat-conducting oil to the heat sink outside the fuel tank of the boost rectifier high-voltage module 200, and the heat sink outside the fuel tank exchanges heat with the air to achieve natural cooling. The boost rectifier high-voltage module 200 includes a boost transformer TR1, an inductor Ls, a high-voltage rectifier circuit ZD2, a sampling circuit, a temperature sensor 2PT100, an oil level sensor K1, and a second external interface. Among them, the sampling circuit includes a first resistor R21, a second resistor R22, and a third resistor R23. The high-voltage rectifier circuit ZD2 includes a diode eight D8, a diode nine D9, a diode ten D10, and a diode eleven D11. The input coil of the boost transformer TR1 is connected in series with the inductor Ls and then electrically connected to the second module interconnection interface 400. One end of the output coil of the boost transformer TR1 is electrically connected to the negative electrode of the diode eight D8 and the positive electrode of the diode nine D9. The other end of the output coil of the boost transformer TR1 is electrically connected to the negative electrode of the diode ten D10 and the positive electrode of the diode eleven D11. The positive electrodes of the diode eight D8 and the diode ten D10 are both electrically connected to one end of the third resistor R23 and the second external interface. The negative electrodes of the diode nine D9 and the diode eleven D11 are both electrically connected to one end of the second resistor R22 and the second module interconnection interface 400. The other end of the third resistor R23 is electrically connected to one end of the first resistor R21. The other end of the third resistor R23 is also electrically connected to the second module interconnection interface 400. The other ends of the second resistor R22 and the first resistor R21 are both electrically connected to the second module interconnection interface 400 and the second external interface. The temperature sensor 2PT100 and the oil level sensor K1 are both electrically connected to the second module interconnection interface 400. The boost rectifier high-voltage module 200 is an independent separation module, and the boost rectifier high-voltage module 200 can be sold as an independent product and can be purchased according to needs during maintenance.

[0104] It should be noted that for other specific embodiments of the control method of the silicon carbide high-voltage power supply in this embodiment, reference can be made to the specific embodiments of the silicon carbide high-voltage power supply above. To avoid redundancy, it will not be elaborated here.

[0105] Example 4

[0106] As Figure 9As shown, a control method for a silicon carbide high-voltage power supply involved in Embodiment 4 of the present application is used to control the silicon carbide high-voltage power supply as described in Embodiment 1. First, it is necessary to collect the DC voltage signal of the three-phase rectifier circuit, the temperature and oil level information of the insulating heat-conducting oil, and the switch signal of the external safety interlock switch. The specific steps are as follows:

[0107] S001. Collect the DC voltage signal of the three-phase rectifier circuit through the monitoring interface QD1;

[0108] S002. Collect the temperature and oil level signals in the fuel tank through the transformer temperature analog input interface and the transformer oil level digital input interface to obtain the temperature and oil level information of the insulating heat-conducting oil;

[0109] S003. Collect the switch signal of the external safety interlock switch through the safety connection lock interface. For example, the external safety interlock switch K2 can be set on the door of the safety protection fence around the boost rectifier high-voltage module 200. During high-voltage operation, when someone tries to open the door of the safety protection fence, the external safety interlock switch K2 disconnects, and the circuit breaker QF1 of the high-voltage power supply can be disconnected before dangerous electric shock occurs, completely disconnecting the high-voltage power supply;

[0110] The control method includes:

[0111] S100. Control the pre-charge circuit of the filter circuit to pre-charge the filter circuit, and control the three-phase rectifier circuit to conduct when the pre-charge of the filter circuit is completed. Specifically, the monitoring interface QD1 of the embedded control system collects the DC voltage of the three-phase rectifier circuit ZD1, and controls the pre-charge circuit of the filter circuit C1 to pre-charge the filter circuit C1, limiting and reducing the current of the zero-voltage charge of the filter circuit C1 during initial power-on, reducing interference. When the charging is completed, the thyristor trigger signal of the three-phase rectifier circuit ZD1 is controlled at the same time to control the conduction of the three-phase rectifier circuit ZD1;

[0112] S200, determine whether a short circuit, fault, or external safety interlock switch is disconnected. Among them, the fault includes signal acquisition and monitoring faults and embedded control system faults. If the judgment result is yes, disconnect the circuit breaker. For example, through its own short-circuit protection function, it can monitor the occurrence of faults, and when a fault is detected, it can completely disconnect the high-voltage power supply by disconnecting the circuit breaker; the embedded control system monitors the signals related to the silicon carbide high-voltage power supply through signal acquisition, and triggers fault protection according to the fault conditions inside the embedded control system software. When a fault occurs, the embedded control system disconnects the circuit breaker QF1 for fault tripping protection; associate the external safety interlock switch K2 with the occurrence of dangerous actions. For example, the external safety interlock switch K2 can be set on the door of the safety protection fence around the boost rectifier high-voltage module 200. During high-voltage operation, when someone tries to open the door of the safety protection fence, the external safety interlock switch K2 is disconnected, so that the circuit breaker QF1 of the high-voltage power supply can be disconnected before the danger occurs, completely disconnecting the high-voltage power supply;

[0113] S300, control the silicon carbide MOSFET inverter circuit to invert direct current into alternating current with adjustable frequency and amplitude through the first PWM drive signal and the second PWM drive signal. Among them, the first PWM drive signal and the second PWM drive signal support two modes: unipolar SPWM modulation and bipolar SPWM modulation;

[0114] The modulation of the first PWM drive signal and the second PWM drive signal includes a linear AC modulation method and a non-linear modulation AC method. The linear AC modulation method controls the linear and stable adjustment of the high-voltage DC output of the high-voltage power supply, and the non-linear modulation AC method controls the high-voltage DC output of the high-voltage power supply to change periodically according to the peak and valley values.

[0115] Specifically, after the direct current is filtered by the filter circuit C1, it supplies power to the silicon carbide MOSFET inverter circuit VT1-VT4. The silicon carbide MOSFET inverter circuit VT1-VT4 is controlled by the first PWM drive signal and the second PWM drive signal of the embedded control system, and inverts the direct current into alternating current with adjustable frequency and amplitude. Through the frequency and amplitude adjustable AC output interface J11, it is connected to the input interface J21 of the primary coil of the transformer in the boost rectifier high-voltage module 200 through the power cable WR1, so as to realize the control of the silicon carbide MOSFET inverter circuit VT1-VT4 through the first PWM drive signal and the second PWM drive signal, and change the output voltage and current of the boost rectifier high-voltage module 200.

[0116] The first PWM drive signal and the second PWM drive signal of the embedded control system support two modes: unipolar SPWM modulation and bipolar SPWM modulation, can be applied to different silicon carbide MOSFET devices, and can bring out the best performance of different silicon carbide MOSFET devices.

[0117] The above are only the preferred specific embodiments of the present application; however, the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution and its improvement concept of the present application, makes equivalent substitutions or changes, and should be covered by the protection scope of the present application.

Claims

1. A silicon carbide high voltage power supply, characterized in that: It includes a silicon carbide MOSFET inverter control module and a boost rectifier high-voltage module, wherein the silicon carbide MOSFET inverter control module has a first module interconnection interface, and the boost rectifier high-voltage module has a second module interconnection interface, and the first module interconnection interface is electrically connected to the second module interconnection interface through a detachable cable; Wherein, the silicon carbide MOSFET inverter control module includes a three-phase rectifier circuit and a controller, the input end of the three-phase rectifier circuit is connected to a first external interface through a circuit breaker, the output end of the three-phase rectifier circuit is connected in parallel with a filter circuit and a silicon carbide MOSFET inverter circuit, the three-phase rectifier circuit is also electrically connected to a monitoring interface, the monitoring interface is electrically connected to the controller, the controller is also electrically connected to a human-machine interaction module and an inverter heat dissipation module, the output ends of the controller and the silicon carbide MOSFET inverter circuit are both electrically connected to the first module interconnection interface, and the controller is also connected to the first external interface; The minimum operating frequency of the silicon carbide MOSFET inverter circuit should satisfy the following formula: ； Among them, F min is the minimum modulation AC frequency of the SiC MOSFET inverter circuit; U p N is the maximum voltage peak of the AC voltage output of the silicon carbide MOSFET inverter circuit; p is the number of turns of the primary coil of the step-up transformer; △Bm is the maximum allowable magnetic density change of the core material of the step-up transformer; S is the cross-sectional area of ​​the core of the step-up transformer.

2. The silicon carbide high voltage power supply according to claim 1, characterized in that: The first module interconnection interface includes a frequency-amplitude modulated AC output interface, a high-voltage output voltage and current analog input interface, a transformer temperature analog input interface and a transformer oil level switch input interface. The frequency-amplitude modulated AC output interface is electrically connected to the silicon carbide MOSFET inverter circuit, and the high-voltage output voltage and current analog input interface, the transformer temperature analog input interface and the transformer oil level switch input interface are all electrically connected to the controller.

3. The silicon carbide high voltage power supply according to claim 2, characterized in that: The first external interface includes a safety connection lock interface, a first grounding interface, a DCS distributed centralized control interface, a host computer monitoring system control interface and a three-phase industrial frequency AC power supply interface. The safety connection lock interface, the first grounding interface, the DCS distributed centralized control interface and the host computer monitoring system control interface are all electrically connected to the controller, the three-phase industrial frequency AC power supply interface is electrically connected to the circuit breaker, the safety connection lock interface is connected to the safety connection lock signal input interface via a cable, and the safety connection lock signal input interface is electrically connected to an external safety interlock switch.

4. The silicon carbide high voltage power supply according to claim 3, characterized in that: The boost rectifier high-voltage module includes a boost transformer, a temperature sensor and an oil level sensor. The input coil of the boost transformer is electrically connected to the second module interconnection interface after being connected in series with an inductor. The output coil of the boost transformer is connected to a high-voltage rectifier circuit. The high-voltage rectifier circuit is connected to a second external interface through a sampling circuit. The high-voltage rectifier circuit is also electrically connected to the second module interconnection interface through the sampling circuit. The temperature sensor and the oil level sensor are both electrically connected to the second module interconnection interface. The primary coil of the step-up transformer is connected in series with the inductor L S , the minimum modulation AC frequency in the SiC MOSFET inverter circuit is at the minimum frequency F min The following formula should be satisfied: ； U1 RMS The maximum effective value of the primary coil input of the boost transformer in the boost rectifier high voltage module; F min is the minimum modulation AC frequency of the SiC MOSFET inverter circuit; L S is the leakage inductance or series inductance of the primary coil of the boost transformer in the boost rectifier high-voltage module; N is the transformation ratio of the boost transformer in the boost rectifier high-voltage module; I2 RMS The effective value of the high voltage rated current output of the boost rectifier high voltage module.

5. The silicon carbide high voltage power supply according to claim 4, characterized in that: The second module interconnection interface includes a transformer primary coil input interface, a high-voltage output voltage and current signal interface, a transformer temperature signal interface and an oil level signal interface, wherein the input coil of the step-up transformer is electrically connected to the transformer primary coil input interface after being connected in series with an inductor, the sampling circuit is electrically connected to the high-voltage output voltage and current signal interface, the transformer temperature signal interface is electrically connected to the temperature sensor, the oil level signal interface is electrically connected to the oil level sensor, the temperature sensor and the oil level sensor are installed in the heat dissipation oil tank of the step-up rectifier high-voltage module, the transformer primary coil input interface is electrically connected to the frequency amplitude modulated AC output interface through a detachable cable, the high-voltage output voltage and current signal interface is electrically connected to the high-voltage output voltage and current analog input interface through a detachable cable, the transformer temperature signal interface is electrically connected to the transformer temperature analog input interface through a detachable cable, and the oil level signal interface is electrically connected to the transformer oil level switch input interface through a detachable cable.

6. The silicon carbide high voltage power supply according to claim 5, characterized in that: The second external interface includes a high voltage interface and a second ground interface, and the high voltage interface and the second ground interface are electrically connected to two ends of the sampling circuit respectively.

7. A control method for a silicon carbide high voltage power supply, used to control the silicon carbide high voltage power supply as claimed in claim 6, characterized in that: The control method comprises: Control the pre-charging circuit of the filter circuit to pre-charge the filter circuit, and control the three-phase rectifier circuit to be turned on when the pre-charging of the filter circuit is completed; Determine whether a short circuit, fault or disconnection of the external safety interlock switch occurs; If the judgment result is yes, the circuit breaker is disconnected; The silicon carbide MOSFET inverter circuit is controlled by a first PWM drive signal and a second PWM drive signal to invert DC power into AC power with modulated frequency and amplitude, wherein the first PWM drive signal and the second PWM drive signal support two modes: unipolar SPWM modulation and bipolar SPWM modulation.

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